May storms becoming more common
Should hurricane season start earlier?
The official start of hurricane season may get shifted into May in coming years, after several consecutive seasons produced storms prior to the current opening date of June 1.
A low-pressure system near the Bahamas has been given a 70% chance of forming a subtropical storm or depression later this week. If it does, this would be the sixth year in a row to see a storm form before the official start date.
Dennis Feltgen, spokesman for the National Hurricane
Center, said the possibility of shifting the opening date into May is being discussed, in light of the series of pre-season storms. Nothing formal has been proposed, he said, but the increase in early storms has led to conversations on the pros and cons of an earlier start date.
“NHC has taken note of the formation of named storms during May 15-31 in about half of the past 10-15 years,” he said in an email Wednesday. “But, it is also aware of the lack of any such activity during May 15-31 in the preceding 30 years. NHC Is weighing the potential advantages and disadvantages of changing the official start date of the
Atlantic hurricane season based on the possibility that the recent uptick in late May storms will continue.”
Hurricane season used to be a month shorter. In 1935, when the predecessor of the National Weather Service set up a hurricane warning network, it established a special telegraph line that operated from June 15 through Nov. 15, Feltgen said. The five months during which the telegraph line operated was hurricane
season.
In 1965 the season was extended to the current dates, June 1 through Nov. 30. About 97% of Atlantic tropical storm activity takes place between these dates, he said. Storms have formed in all the other months of the year, he said, with May being the most active of the non-season months.
John Nielsen-Gammon, professor of meteorology at Texas A&M University and the Texas State Climatologist, said much of the Atlantic is unusually warm now, creating conditions that would normally prevail about two weeks later in the year. But he said it’s unclear whether it would be worth it to discuss an earlier start date for future seasons.
“The storms don’t care,” he said. “The only thing that matters really is it tends to kick off people paying attention to hurricanes. That may be somewhat less relevant, since we’ve gotten saturated with weather forecaster information, The Weather Channel and so forth. I could understand not wanting to do it because you’d suddenly get all these existential political arguments about oh they’re just doing that because of climate change or something.”
The prospect of a longer hurricane season may not be the best news these days, especially when we’re already getting prepared to deal with a different “new normal.”
But of course, nature will do what it will do, regardless of official start dates. And scientists point out that early-season storms are typically weak. They tend to form fairly close to shore, almost never reach hurricane strength and bear little resemblance to the potential monsters that form near Africa later in the season and gather power during their long journey across the Atlantic. No one expects a Dorian or Andrew to form in May.
Dan Kottlowski, chief hurricane forecaster, for AccuWeather, said scientists have discussed extending the season about 15 days into May. Although initial conversations weren’t that serious, he said the parade of early-season storms has changed that.
“A few years ago, they were joking about it, but over the last five years or so, I’ve seen more serious discussion,” he said. “If you look at the past 30 or 40 years, it doesn’t really make sense right now. But if this continues over the next five years or so, then maybe statistics will force us to do that.”
Each year since 2015 has seen a storm form prior to the official date. Last year Subtropical Storm Andrea formed May 20 far out in the Atlantic, barely held subtropical storm strength of 40 mph and fell apart a day later without threatening land. A particularly early storm arose in 2017, when Tropical Storm Arlene formed in the northern Atlantic and reached a top wind speed of 50 mph.
Although early storms are typically unimpressive, an exception took place in 2018 with Tropical Storm Alberto. The storm formed May 25, achieved a wind speed of 65 mph, just 9 mph short of hurricane strength, and struck Cuba and the Florida Panhandle, leaving 18 dead.
Phil Klotzbach, research scientist for Colorado State University’s Tropical Meteorology Project, said there’s little reason to move up the start date. One reason we’re seeing more storms early in the season, he said, is improved technology that allows scientists to better detect weak storms that quickly dissipate.
“I don’t think it’s worth extending the hurricane season, since the continental U.S. has never witnessed a hurricane landfall prior to June 1,” he said. “Also we’ve only had two years in the satellite era [since 1966] where the Atlantic has had a hurricane prior to June 1: 1970 and 2016. Most of these pre-June storms are quite weak.”
Any change in the start date would involve discussions among the National Hurricane Center, other governmental agencies and the World Meteorological Organization.
Is climate change a factor in the increase in early-season storms? It’s unclear. Many scientists think global warming could lead to stronger hurricanes, but they also think it could lead to fewer of them. Warmer water fuels hurricanes, making them stronger. But climate change could increase periods of high-altitude crosswinds that tend to prevent hurricane structures from forming.
David Nolan, chairman of the Department of Atmospheric Sciences at the University of Miami, said, the warm ocean water fueling the potential storm is the result of a short-term heatwave, not the slower, longer-term effect of climate change.
“Global warming and a trend in hurricane activity has not been established,” he said. “You can guess, but scientifically the evidence is not there. There’s no evidence we’re going to have more April or May tropical cyclones because of global warming.”
Since most studies on climate change and hurricane predict stronger, but fewer, storms, he said, “That would actually suggest less storms than April or May.”